Hot-melt adhesive composition

ABSTRACT

The present invention is directed to a hot-melt adhesive containing at least one propylene/1-hexene copolymer. The adhesive contains an amount of a low viscosity, substantially crystalline wax, having a melting point of about 90° C. to about 125° C., sufficient to improve the elastic delamination resistance of the adhesive. The adhesives are particularly useful in disposible diaper construction.

This application is a continuation-in-part of application Ser. No.126,439, filed November 30, 1987, now abandoned.

FIELD OF INVENTION

The present invention concerns hot-melt adhesives (HMAs) containing atleast one propylene/hexene copolymer useful as disposable diaperadhesives.

BACKGROUND OF THE INVENTION

Recent trends in the design of disposable diapers have necessitated thedevelopment of more versatile adhesives for use in the diapers. Thetrend of the industry toward diapers with elastic bands on either thelegs or the waist of the diaper have made it necessary to use a strongermore delamination resistant adhesive to hold the elastic in place. Mostdiaper manufacturers prefer to use one hot-melt adhesive to bothconstruct the diaper (that is to bind the nonwoven top sheet and fillerto the polyethylene back sheet) and to hold the elastic on the leg orwaist of the diaper. It is well known that polyolefin based HMAs aresuitable for the construction of diapers by construction techniques ascurrently practiced such as multiple fine line, hot-melt spray, hot-meltfoam, slot coating operations, and various screen coating methods.However, polyolefin-based HMAs are traditionally not suitable for thebonding of the elastic to the diapers, that is, the elastic delaminationresistance is insufficient for such an application. For this reason,adhesives based on styrene rubbers such as S-I-S block copolymers orS-B-S block copolymers are used (see, for example, U.S. Pat. No.4,526,577).

The use of two HMAs on the same diaper poses some problems for thediaper manufacturer. They must insure the right adhesive is used in theright melt tank and is applied to the correct place on the diaper.Therefore, an adhesive that is capable of performing both types ofbonding functions is highly desirable.

Wax is traditionally added to hot-melt adhesives with the objective ofcontrolling viscosity of the adhesive. That is, it is a diluent and mayin some cases lower the cost of the adhesive. For the most part waxesare not known to add to the strength of HMAs but rather are used tocontrol set time or open time or viscosity.

This invention describes a polyolefin-based HMA suitable for use as boththe adhesive of construction of disposable diapers and as the adhesiveto hold the elastic onto the leg or waistband. Thus a universal diaperadhesive based on polyolefins has been developed. It has beensurprisingly found that the addition of a low viscosity, substantiallycrystalline wax to a polyolefin-based HMA substantially improves theelastic delamination resistance. The formulation of an HMA containing anolefin-based polymer having sufficient elastic delamination resistanceto meet the demands of the universal diaper adhesive is a significantadvance in the art.

SUMMARY OF THE INVENTION

The present invention is directed to a hot-melt adhesive compositionwhich has a blend of properties that makes it ideally suited for usewith disposable diapers.

More specifically, the present invention is directed to a hot-meltadhesive composition having a viscosity of about 3,000 to about 25,000centipoise at 135° C. and a Ring and Ball softening point of about 90°C. to about 125° C., said adhesive composition comprising a blend of:

(a) at least one substantially amorphous propylene/hexene copolymerhaving an acid number of less than about 0.5,

(b) at least one tackifier, and

(c) at least one substantially crystalline, low viscosity hydrocarbonwax containing substantially no propylene and having a melt viscosity offrom about 3 to about 4,000 centipoise at 150° C. and a melting point offrom about 90° C. to about 125° C., the concentration of components (a),(b), and (c) being such that said adhesive composition has an elasticdelamination resistance of at least about 4 hours wherein elasticdelamination resistance is the length of time a polyethylene to elasticbond can withstand the stress of elastic relaxation at body temperature.

Most preferably, the composition of the present invention is a hot-meltadhesive composition having a viscosity of about 3,000 to about 25,000centipoise at 135° C. and a Ring and Ball softening point of about 90°C. to about 125° C., said composition comprising a blend of:

(i) about 30 to about 70 weight percent of at least one substantiallyamorphous propylene/hexene random copolymer containing from about 20 toabout 50 weight percent of 1-hexene, said polymer having a meltviscosity of from about 2,000 to about 20,000 centipoise at 190° C.,

(ii) about 20 to about 50 weight percent of at least one solid tackifiercomprising hydrocarbon resins or polyterpene resins, said solidtackifier having a Ring and Ball softening point of from about 70° C. toabout 145° C.,

(iii) 0 to about 30 weight percent of at least one liquid tackifierhaving a viscosity of from about 5 to about 500 centipoise at 95° C. anda Ring and Ball softening point of from about 5° C. to about 30° C.,

(iv) from about 1 to about 10 weight percent of at least onesubstantially crystalline, low viscosity hydrocarbon wax containingsubstantially no propylene and having a melt viscosity of from about 3to about 4,000 centipoise at 150° C. and a melting point of from about90° C. to about 125° C., and

(v) 0 to about 30 weight percent of at least one plasticizing oil.

The present invention is also directed to a method for applying thecompositions of the invention to a disposable diaper and to articlescomprising the composition of the invention in combination with adisposable diaper.

DETAILED DESCRIPTION OF THE INVENTION

The adhesive compositions of the present invention preferably have amelt viscosity of about 4,000 to about 10,000 centipoise at 135° C.,more preferably about 5,000 to about 9,000. Melt viscosities of theadhesive compositions and the various components thereof can bedetermined using a Brookfield Model RTV Thermosel viscometer using aNumber 27 spindle in accordance with American Society for Testing andMaterials (ASTM) Procedure 1824-66.

The adhesive compositions of the present invention preferably have aRing and Ball softening point (RBSP) of about 100° C. to about 125° C.,more preferably about 112° C. to about 120° C. RBSP for the adhesivecompositions and various components thereof can be determined by use ofASTM Procedure E-28.

The Gardner color of the adhesive compositions of the present inventionpreferably is less than about 7, most preferably less than about 3.Gardner color for the adhesive compositions and various componentsthereof can be determined by use of ASTM Procedure D-1544.

Bond strength of the adhesives of the present invention is at leastabout 200 grams based on an adhesive coating weight of 2.1 milligrams(mg) per inch, preferably at least 300 grams. At about 300 gramssubstrate failure occurs. Bond strength can be measured by thecontrolled destruction of the bonds by an Instron tensile tester at 10inches per minute (min.). More specifically, nonwoven fabric (e.g.,polypropylene or polyester nonwoven fabric commonly used in disposablediaper construction) is bonded by applying a single 2.1 mg per inch beadof adhesive on a moving web of polyethylene film at a melt temperatureof 140° C., then applying sufficient nip pressure to bring the twosubstances in contact. The open time is about 1 second, and thecompression time is less than 0.5 seconds. The nonwoven fabric is thenpulled from the polyethylene in a T-peel mode and the average amount offorce required to pull apart the two substances is the bond strength.

Tensile strength of the adhesive compositions of the present inventionis typically greater than about 10 pounds per square inch (psi), andpreferably about 20 to about 50 psi. Tensile strength can be determinedby use of ASTM Procedure D-638-72.

The Cone penetration value of the adhesive compositions of the presentinvention is typically greater than about 10 decimillimeters (dmm), andpreferably greater than about 20 dmm. Cone penetration can be measuredby use of ASTM Procedure D-1403.

The elastic delamination resistance of the compositions of the presentinvention is greater than about 4 hours, preferably greater than about 8hours, more preferably greater than about 24 hours, and most preferablygreater than about 100 hours. The elastic delamination resistance isdetermined by the following procedure:

Elastic, 0.25 inches wide and 0.007 inches thick, typically used indisposable diaper construction (can be obtained from Fulflex Company) isexpanded to 100% elongation. Test adhesive is applied as a bead at 275°F. to the elongated elastic which is then immediately brought intocontact with polyethylene film and passed through a compression roller.The hot-melt adhesive bead weight is controlled at 10 to 15 mg perlinear inch of polyethylene film. The polyethylene film is 1-2 milsthick and is a low density polyethylene blended with linear low densitypolyethylene or high density polyethylene. The polyethylene film ispigmented with TiO₂ and corona treated and is typical of polyethylenefilm used in disposable diaper manufacture. The bonded material isallowed to relax and age overnight. After aging, specimens 8-inches longare cut. The center 6 inche sections of the specimens are elongated to12 inches (100% elongation) and then the polyethylene is clamped in ametal jig with the elastic surface up. The elastic is not clamped. Thespecimens are then placed in an oven at 100° F. for various times. Thetime at which a visible, continuous delamination or end release isobserved is the elastic delamination resistance.

The adhesive compositions of the present invention contain at least onesubstantially amorphous propylene-hexene copolymer with an acid numberless than about 0.5. The propylene/hexene copolymer is preferablypresent as an amount of 30 to about 70 weight percent of the adhesivecomposition, more preferably about 40 to about 65 weight percent andmost preferably about 43 to about 53 weight percent. Such copolymers areknown to be useful in adhesive formulations and are commerciallyavailable. The propylene/hexene copolymers can be prepared usingtechniques known in the art, for example, by use of the techniquesdisclosed in U.S. Pat. Nos. 3,954,697 and 4,259,470, both of which areincorporated herein by reference.

Preferred propylene/hexene copolymers have a melt viscosity of fromabout 2,000 to about 20,000 centipoise (cp) at 190° C., more preferablyabout 4,000 to about 20,000 cp, and most preferably about 5,300 to about6,100 cp. Preferred copolymers are random copolymers having a 1-hexenecontent of about 20 to about 50 weight percent, more preferably about 30to about 40 weight percent, and most preferably about 32 to about 36weight percent. It is preferred that the RBSP for such copolymers isabout 100° C. to about 134° C., preferably about 129° C. to about 134°C.

The low viscosity, substantially crystalline hydrocarbon wax in theadhesive composition of the present invention is present in an amountsufficient to improve the elastic delamination resistance of thecomposition. Typically this amount is about 1 to about 10 weight percentof the composition, preferably about 3 to about 7 weight percent. Thehydrocarbon waxes in the adhesive compositions of the present inventionare widely available articles of commerce and can be prepared by knowntechniques. These waxes are preferably polyethylene waxes. Suchpolyethylene waxes can be made by direct synthesis or by degradingpolyethylene, preferably high density polyethylene (i.e., ≧ about 0.94grams(g)/cubic centimeters (cc)) to the desired viscosity. The waxeshave a melt viscosity of from about 3 to about 4,000 centipoise at 150°C., preferably about 3 to about 1,000 centipoise, and most preferablyabout 300 to about 700 centipoise; and a melting point of from about 90°C. to about 125° C., preferably about 105° C. to about 125° C., and mostpreferably about 120° C. to about 125° C. The waxes also preferably havea cone penetration hardness at 23° C. of about 0.1 dmm to about 10 dmm.Penetration hardness can be measured by ASTM procedure D-1321-76.Specific waxes useful in the present invention include Epolene C-15 andEpolene N-45, available from Eastman Chemical Products, Inc., Bareco1000 and Bareco BE² 195, available from Petrolite Corp., and ParaflintH1, available from Moore and Munger, Inc. Preferred are Bareco 1000 andEpolene N-45.

The adhesive compositions of the present invention typically contain oneor more tackifiers in an amount of about 20 to about 60 weight percentof the composition. Solid tackifiers are typically present in an amountof from 20 to 50 weight percent, preferably 25 to 40 weight percent, andmost preferably about 24 to about 29 weight percent. The solidtackifiers can be hydrocarbon resins such as DAC-B hydrocarbon resinprepared according to the process disclosed in U.S. Pat. No. 3,701,760as well as other hydrocarbon resins, polyterpenes, and the like. Onesuch hydrocarbon tackifying resin is a hydrocarbon resin having asoftening point of about 130° C. and available commercially as EastotacH-130 from Eastman Chemical Products, Inc. Other hydrocarbon tackifyingresins can be prepared by the polymerization of monomers consistingprimarily of olefins and diolefins and include, for example, theresidual by-product monomers resulting from the manufacture of isoprene.These hydrocarbon tackifying resins typically exhibit a RBSP of fromabout 70° C. to about 145° C., preferably about 125° C. to about 135°C.; an acid number of from about 0-2, a saponification value of lessthan about 1; and an iodine value of from about 30 to 100. It is alsopreferred that such tackifiers have a melt viscosity at 190° C. of about600 to about 1,600 cp. Examples of such commerically available resinsbased on a C₅ -olefin fraction of this type are "Wingtack" 95 and"Wingtack" 115 tackifying resins sold by Goodyear Tire and RubberCompany, the Sta-Tac and Betaprene A or H resins sold by ReichholdChemical Corporation, and Escorez resins sold by Exxon Chemical Co.

Also, other suitable solid tackifier resins are the terpene polymerssuch as the polymeric, resinous materials obtained by polymerizationand/or copolymerization of terpene hydrocarbons such as the alicyclic,monocyclic, and bicyclic monoterpenes and their mixtures, includingalloocimene, carene, isomerized pinene, pinene, dipentene, terpinene,terpinolene, limonene, terpentine, a terpene cut or fraction, andvarious other terpenes. Particularly useful starting materials areterpene mixtures containing at least 20 percent beta-pinene and/orlimonene or dipentene (racemic limonene), and the "sulfate terpentine"obtained as a by-product in the sufate pulping process. Commerciallyavailable resins of the terpene type include the Zonarez terpeneB-Series and 7000 Series resins from Arizona Chemical Corp. and Nirezresins from Reichhold Chemical Corp. The typical properties reported forthe Zonarez terpene resins include RBSPs of about 55° to 125° C. (ASTME-28-67), color of 2 to 3 (Gardner 1963, 50% in heptane), acid number ofless than 1 (ASTM D465-59), saponification number of less than 1 (ASTMD464-59) and specific gravity at 25° C. of about 0.96 to about 1.00(ASTM D1963-61).

The liquid tackifiers are typically present in an amount of from 0 toabout 30 weight percent of the adhesive composition, preferably about 15to about 25 weight percent, and most preferably about 18 to about 22weight percent. The liquid tackifiers are commercial items and/or can beprepared by techniques known in the art, for example, by the techniquesdescribed in U.S. Pat. No. 3,872,064, incorporated herein by reference.The liquid tackifiers are preferably liquid hydrocarbon resins such assynthetic polyterpene or other petroleum hydrocarbon resins. Specificexamples include "Wingtack" 10 from Goodyear Tire and Rubber Company and"Escorez" 2520 (also known as ECR-140) from Exxon Chemical Co. Theliquid tackifiers have a melt viscosity of about 10,000 to about 50,000cp at 23° C., preferably about 20,000 to about 40,000; a RBSP of about5° C. to about 30° C., preferably about 10° C. to about 20° C., and aglass transition temperature (Tg) as measured by differential scanningcalorimetry (DSC) of about -10° C. to about -30° C., preferably about-20° C. to about -30° C. A liquid tackifier is particularly useful incompositions containing a solid tackifier and substantially noplasticizing oil.

The compositions of the present invention can also optionally contain 0to 30 weight percent of at least one plasticizing oil, preferred isabout 1 to about 25 weight percent, and most preferred is about 5 to 20weight percent. A plasticizing oil is particularly useful incompositions containing a solid tackifier and substantially no liquidtackifier. A description of suitable plasticizing oils can be found inU.S. Pat. No. 4,210,570, incorported herein by reference. Operableplasticizing oils include paraffinic/naphthenic oils such as Shellflex371, Tuflo 6204 and Kaydol oils, Abietol (Hercules trade name for woodrosin derivative), and polymerized DAC-B oils such as Plasticizer H.Also operable are esters derived from either aromatic or aliphatic acidswhich have a boiling point of greater than about 275° C. at 760 mmpressure. Useful esters include materials such astris(2-ethylhexyl)trimellitate, bis(2-ethylhexyl)-phthalate,bis(2-ethylhexyl)terephthalate, dibutyl sebacate,bis(2-ethylhexyl)adipate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate,methyl abietate, and the like. Suitable plasticizing oils have a Tg asmeasured by DSC of - 60° C. or less. Preferred plasticizing oils have aviscosity of about 325-425 Saybolt Universal Seconds (SUS) at 100° F.(37.8° C.) and a specific gravity of about 0.85-0.92 g/cc at 25° F. Aspecific, preferred plasticizing oil is Witco 380 from Witco ChemicalCompany, Sonneborn Division, Houston, Texas, U.S.A.

The adhesive compositions of this invention are prepared by blendingtogether the adhesive components in the melt at a temperature of about160° C. to about 200° C. until a homogeneous mixture is obtained.Various methods of blending materials of this type are known to the artand any method that produces a homogeneous mixture is satisfactory.These components blend easily in the melt and a heated vessel equippedwith a stirrer is all that is required. For example, a Cowles stirrerprovides effective mixing for preparing these compositions. Solventssuch as hexane, heptane, mineral spirits, xylene, toluene, benzene,chlorinated hydrocarbons, etc., are not needed to prepare thecompositions of this invention: however, they can be used if desired.

In addition to the hereinabove described adhesive components, it isdesirable for the adhesive compositions to contain about 0.1 percent toabout 1.5 percent by weight, preferably about 0.25 percent to 1.0percent by weight, and most preferably about 0.3 to about 0.6 percent byweight, of one or more antioxidants. Antioxidants that are effectiveinclude, for example, tris(di-t-butyl-p-hydroxybenzyl)-trimethylbenzene(Ionox 330), alkylated bisphenol (Naugawhite), zinc dibutyldithiocarbamate (Butyl Zimate), and 4,4'-methylenebis(2,6-di-tert-butylphenol) (Ethyl 702),tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate(methane](Irganox 1010), lauryl stearyl thiodipropionate (Cyanox 1212), anddilauryl 3,3'-thiodipropionate (Cyanox LTDP) and2,6-di-tert-butyl-p-cresol (BHT) and the like.

Additional additives such as nucleating agents, pigments, colorants,fillers, solvents, and the like can also be added to the adhesivecompositions of the present invention.

The adhesive compositions of the present invention can be made into anyphysical form typically used in the art. When formed into slats, thecompositions typically are coated with a wax which may or may not be awax within the scope of the invention.

In the method of the present invention, the adhesive composition isapplied to a disposable diaper or portion thereof using techniques knownin the art. For example, the adhesive composition can be applied bymultiple fine line, hot-melt spray, hot-melt foam, slot coatingoperations, and various screen coating methods. The amount of adhesivecomposition applied to a diaper is that amount sufficient to result inbonds that will withstand typical storage and end use conditions. It iscontemplated that the adhesive compositions of the present invention areuseful in applications other than diapers, for example, in sanitarynapkins and bed pad construction.

In the adhesive compositions of the present invention, as appreciated byone skilled in the art, the particular proportions of componentsnecessary to achieve specific desired properties will vary depending onthe nature of the particular components.

This invention can be further illustrated by the following examplesthereof, although it will be understood that these examples are includedmerely for purposes of illustration and are not intended to limit thescope of the invention.

EXAMPLES 1-2

An adhesive composition was made in accordance with the presentinvention containing 5 weight % of a hydrocarbon wax as described herein(Example 2). For comparison, an adhesive composition outside the scopeof the invention, i.e., not containing a hydrocarbon wax, was alsoprepared (Example 1). The two compositions were tested for theirrespective elastic delamination resistance (EDL). As shown in Table 1,the EDL of Example 1 was only four hours, whereas the EDL of Example 2was greater than 100 hours.

                  TABLE 1                                                         ______________________________________                                        ADHESIVE BLENDS                                                               EXAMPLE NUMBER           1      2                                             ______________________________________                                        COMPOSITION (Weight %)                                                        .sup.1 APH 5             26     26                                            .sup.2 APH 3             17     22                                            .sup.3 Eastotac H-130W   36.5   26.5                                          .sup.4 Escorez 2520      20     20                                            .sup.5 Bareco 1000       --     5.0                                           .sup.6 Irganox 1010      0.5    0.5                                           BLEND PROPERTIES                                                              VISCOSITY @ 135° C., cp                                                                         9600   6600                                          RBSP, °C.         113    108                                           CONE PENETRATION, dmm    18     14                                            TENSILE STRENGTH, psi    15     30                                            ELASTIC DELAMINATION RESISTANCE                                               Time to failure, hrs     4      >100                                          BOND STRENGTH, grams     200    300 (sub-                                                                     strate                                                                        failed)                                       ______________________________________                                         .sup.1 APH 5 = amorphous propylene/1hexene copolymer having a viscosity o     17,000 cp at 190° C., 23 weight % 1hexene content, and a RBSP of       138° C.                                                                .sup.2 APH 3 = amorphous propylene/1hexene copolymer having a viscosity o     3,000 cp at 190° C., 55 weight % 1hexene content, and a RBSP of        114° C.                                                                .sup.3 Eastotac H130W = solid tackifier, petroleum hydrocarbon resin, RBS     of 130°  C. melt viscosity at 190° C. of 1,000 cp.              .sup.4 Escorez 2520 = liquid tackifier, RBSP of 20° C., Tg of          -20° C., melt viscosity of 40,000 cp at 23° C.                  .sup.5 Bareco 1000 = high density, low viscosity, crystalline polyethylen     wax, melting point of 113° C., penetration hardness of 1 dmm,          density of 0.96 g/cc, melt viscosity of 11 cp at 150° C.               .sup.6 Irganox 1010 = antioxidant                                        

EXAMPLES 3-8

Adhesive blends having a relatively high proportion ofpropylene/1-hexene copolymer (i.e. 47%) were prepared in accordance withthe present invention. The RBSPs of the blends were varied primarily byadjusting the % hexene content of the copolymer. Variations in theelastic delamination resistance (EDL) were observed, however, in allcases the EDLs were greater than four hours as shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________    ADHESIVE BLENDS                                                               EXAMPLE NUMBER         3  4   5   6   7  8                                    __________________________________________________________________________    BLEND COMPOSITION (Wt %)                                                      .sup.1 APH             47.0                                                                             47.0                                                                              47.0                                                                              47.0                                                                              47.0                                                                             47.0                                 .sup.2 Escorez 2520    19.5                                                                             19.5                                                                              19.5                                                                              19.5                                                                              19.5                                                                             19.5                                 .sup.3 Eastotac H-130W 26.0                                                                             26.0                                                                              26.0                                                                              26.0                                                                              26.0                                                                             26.0                                 .sup.4 Bareco 1000     3.0                                                                              3.0 3.0 3.0 3.0                                                                              3.0                                  .sup.5 Epolene C-15    4.0                                                                              4.0 4.0 4.0 4.0                                                                              4.0                                  .sup.6 Irganox 1010    0.5                                                                              0.5 0.5 0.5 0.5                                                                              0.5                                  PHYSICAL PROPERTIES OF APH                                                    Viscosity @ 375° F., cp                                                                       5475                                                                             8325                                                                              7650                                                                              9550                                                                              7000                                                                             5300                                 RBSP, °C.       132                                                                              138 135 132 124                                                                              126                                  Wt. % Hexene           36 33  35  36  40 40                                   PHYSICAL PROPERTIES OF BLEND                                                  Viscosity @ 135° C., cp                                                                       8500                                                                             22750                                                                             29000                                                                             19000                                                                             7750                                                                             6440                                 RBSP, °C.       111                                                                              120.5                                                                             116.5                                                                             112 107                                                                              107                                  Cone Penetration, dmm  25 23.5                                                                              24  22  23 26                                   ELASTIC DELAMINATION RESISTANCE                                               Time to failure, hrs   >47                                                                              >47 >4  >4  >4 >8                                   __________________________________________________________________________     .sup.1 APH = amorphous propylene/1hexene copolymer                            .sup.2 Escorez 2520 = liquid tackifier, RBSP of 20° C., Tg of          -20° C., melt viscosity at 23° C. of 40,000 cp.                 .sup.3 Eastotac H130W = solid tackifier, petroleum hydrocarbon resin, RBS     of 130° C., melt viscosity at 190° C. of 1,000 cp.              .sup.4 Bareco 1000 = high density, low viscosity, crystalline polyethylen     wax, melting point of 113° C., penetration hardness of 1 dmm,          density of 0.96 g/cc, melt viscosity of 11 cp at 150° C.               .sup.5 Epolene C15 = lower density, low viscosity, crystalline                polyethylene wax, melting point of 102° C., penetration hardness o     4 dmm, density of 0.91 g/cc, melt viscosity of 3,900 cp at 150° C.     .sup.6 Irganox 1010 = antioxidant                                        

EXAMPLES 9-16

Adhesive blends were prepared in accordance with the present invention.The compositions and properties of these blends are shown in Table 3.Example 14 is a comparative example without a wax.

                                      TABLE 3                                     __________________________________________________________________________    ADHESIVE BLENDS                                                               EXAMPLE NUMBER          9    10   11   12    13   14 15   16                  __________________________________________________________________________    COMPOSITION (Wt. %)                                                           .sup.1 APH              48   --   48   48    48   50.5                                                                             50   45.7                .sup.2 APB              --   54.5 --   --    --   -- --   --                  .sup.3 Eastotac H-130W  26.5 20   26.5 26.5  26.5 27.9                                                                             17.6 25.2                .sup.4 Escorez 2520     20   20   20   20    20   21.1                                                                             20.8 19                  .sup.5 Bareco 1000      5    --   --   --    --   -- --   --                  .sup.6 Epolene N-45     --   5    --   --    --   -- 1    10                  .sup.7 Epolene C-15     --   --   5    --    --   -- --   --                  .sup.8 Bareco Be.sup.2 195                                                                            --   --   --   5     --   -- --   --                  .sup.9 Paraflint H-1    --   --   --   --    5    -- --   --                  .sup.10 Irganox 1010    0.5  0.5  0.5  0.5   0.5  0.5                                                                              0.5  0.5                 __________________________________________________________________________    PHYSICAL PROPERTIES OF                                                        APH AND APB                                                                   Viscosity @ 375° F.                                                    (190° C.), cp    5475 10000                                                                              5475 5475  5475 5475                                                                             5475 5475                RBSP, °C.        132  110  132  132   132  132                                                                              132  132                 Wt. % Hexene            36   0    36   36    36   36 36   36                  Wt. % Butene            0    40   0    0     0    0  0    0                   PHYSICAL PROPERTIES OF WAX                                                    Melting point, °C.                                                                             113  123  102  91    13   -- 123  123                 Density, g/cc           0.96 0.95 0.91 0.93  0.94 -- 0.95 0.95                Viscosity @ 150° C.,                                                   cp                      11   500  3900 3     3    -- 500  500                 Wax type                ethylene                                                                           ethylene                                                                           ethylene                                                                           micro-                                                                              Fischer-                                                                           -- ethylene                                                                           ethylene                                                   crystalline                                                                         Tropsch                          Penetration                                                                   Hardness, dmm           0.5  0.1  4    7     2    -- 0.1  0.1                 BLEND PROPERTIES                                                              VISCOSITY @ 135° C.,                                                   cp                      8000 10500                                                                              8000 4880  4880 6880                                                                             7100 4200                RBSP, °C.        117  117  117  111   103  113                                                                              115  117                 CONE PENETRATION,                                                             dmm                     17   18   39   10    18   42 33   14                  ELASTIC DELAMINATION RESISTANCE                                               Time to failure, hrs    24   24   24   24    24   <1 24   >72                 __________________________________________________________________________     .sup.1 APH = amorphous propylene/1hexene copolymer                            .sup.2 APB = amorphous propylene/1butene copolymer                            .sup.3 Eastotac H130W = solid tackifier                                       .sup.4 Escorez 2520 = liquid tackifier                                        .sup.5 Bareco 1000 = wax                                                      .sup.6 Epolene N45 = wax                                                      .sup.7 Epolene C15 = wax                                                      .sup.8 Bareco Be.sup.2 195 = wax                                              .sup.9 Paraflint H1 = wax                                                     .sup.10 Irganox 1010 = antioxidant                                       

EXAMPLES 17-25

Adhesive blends were prepared in accordance with the present invention.The compositions and properties of these blends are shown in Table 4.Example 17 is a typical example of the invention. Examples 18 and 19 arecomparative examples using a paraffin wax outside the scope of thepresent invention which does not provide the required elasticdelamination resistance. Example 20 is a control comparative examplewith no wax which does not have the required elastic delaminationresistance. Example 21 is an example of the present inventionillustrating the use of only one tackifier. Examples 22-25 are examplesof the present invention which illustrate the use of a plasticizing oil.

                                      TABLE 4                                     __________________________________________________________________________    ADHESIVE BLENDS                                                               EXAMPLE NUMBER         17  18  19  20  21  22  23 24 25                       __________________________________________________________________________    BLEND COMPOSITION (Wt. %)                                                     .sup.1 APH 1           48  48  43  50.5                                                                              48  --  -- -- --                       .sup.2 APH 2           --  --  --  --  --  50  50 50 50                       .sup.3 Escorez 2520    20  20  20  21.1                                                                              --  --  -- -- --                       .sup.4 Eastotac H-130W 26.5                                                                              26.5                                                                              26.5                                                                              27.9                                                                              --  38.5                                                                              35.5                                                                             32.5                                                                             29.5                     .sup.5 Nirez M-85      --  --  --  --  46.5                                                                              --  -- -- --                       .sup.6 Epolene N-45    5   --  --  --  --  4   4  4  4                        .sup.7 Moore & Munger  --  5   10  --  --  --  -- -- --                       R-0845                                                                        .sup.8 Witco 380       --  --  --  --  --  7   10 13 16                       .sup.9 Bareco 1000     --  --  --  --  5   --  -- -- --                       .sup.10 Irganox 1010   0.5 0.5 0.5 0.5 0.5 0.5 0.5                                                                              0.5                                                                              0.5                      BLEND PROPERTIES                                                              Viscosity                                                                     @ 225° F., cp   500000                                                                            197500                                                                            360000                                                                            70250                                                                             47500                                  @ 275° F., cp   7940                                                                              6000                                                                              2450                                                                              6875                                                                              7560                                                                              11800                                                                             9400                                                                             7440                                                                             6265                     @ 325° F., cp   2475                                                                              2315                                                                              890 1990                                                                              2400                                   RBSP, °C.       112 106.5                                                                             110 113 107 115.5                                                                             116                                                                              115.5                                                                            115                      Cone Penetration, dmm  20  36  21.5                                                                              42.5                                                                              11  10.5                                                                              13.5                                                                             19.5                                                                             24                       ELASTIC DELAMINATION RESISTANCE                                               Time to Failure, hrs   >8  ≦1                                                                         ≦1                                                                         ≦1                                                                         >8  >8  >8 >8 >8                       __________________________________________________________________________     .sup.1 APH 1 = amorphous propylene/hexene copolymer having 38 wt. % hexen     (melt viscosity of 6000 cps at 190° C., 126° C. RBSP)           .sup.2 APH 2 = amorphous propylene/hexene copolymer having 37 wt. % hexen     (melt viscosity of 5500 cps at 190° C., 128° C. RBSP)           .sup.3 Escorez 2520 = liquid tackifier (see Table 2 for properties)           .sup.4 Eastotac H130W =  solid tackifier (see Table 2 for properties)         .sup.5 Nirez M85 = solid tackifier which is an aromatic modified              polyterpene resin made by Reichhold Chemicals, Inc., White Plains, New        York; RBSP of 82-88° C., specific gravity of 0.995                     .sup.6 Epolene N45 = wax (see Table 3 for properties)                         .sup.7 Moore and Munger R0845 = paraffin wax (melt viscosity of 43 cp at      210° F. (99° C.), 145° F. (63° C.) melting        point, 16 dmm cone penetration), available from Moore and Munger              Marketing, Inc., 140 Sherman Street, Fairfield, Connecticut 06430             .sup.8 Witco 380 = plasticizing oil, viscosity of 375 SUS at 100°      F. (37.8° C.), specific gravity at 25° F. of 0.8664             .sup.9 Bareco 1000 = wax (see Table 3 for properties)                         .sup.10 Irganox 1010 = antioxidant                                       

EXAMPLES 26-28

Adhesive blends were prepared in accordance with the present invention.The compositions and properties of these blends are shown in Table 5.Example 26 is a control comparative example without a wax. Example 27 isa typical example of the present invention with 5% wax. Example 28 is acomparative example wherein a wax outside the scope of the invention wasused which does not provide the required elastic delaminationresistance.

                  TABLE 5                                                         ______________________________________                                        ADHESIVE BLENDS                                                               EXAMPLE NUMBER       26      27      28                                       ______________________________________                                        BLEND COMPOSITION (Wt %)                                                      .sup.1 APH           50.5    48.0    48.0                                     .sup.2 Escorez 2520  21.1    20.0    20.0                                     .sup.3 H130W         27.9    26.5    26.5                                     .sup.4 N45           --      5.0     --                                       .sup.5 Moore & Munger R-4044                                                                       --      --      5.0                                      .sup.6 Irganox 1010  0.5     0.5     0.5                                      PHYSICAL PROPERTIES                                                           Viscosity @ 275° F.                                                                         8538    7400    5350                                     RBSP, °C.     112.8   116.8   110.5                                    Cone Penetration, dmm                                                                              30.5    14.0    27.0                                     ELASTIC DELAMINATION                                                          RESISTANCE                                                                    Time to failure, hrs ≦4                                                                             >24     ≦4                                ______________________________________                                         .sup.1 APH = amorphous propylene/hexene copolymer having 34 wt % hexene,      RBSP of 131.5° C. melt viscosity of 5700 cp at 190° C.          .sup.2 Escorez 2520 = liquid tackifier (see Table 2 for properties)           .sup.3 Eastotac H130W = solid tackifier (see Table 2 for properties)          .sup.4 N45 = wax (Epolene N45, see Table 3 for properties)                    .sup.5 Moore & Munger R4044 = paraffin wax, viscosity of 41 cp at             210°  F. (99° C.), melting point of 142° F.              (61° C.), cone penetration hardness of 13 dmm, density of 0.79 g/c     .sup.6 Irganox 1010 = antioxidant                                        

We claim:
 1. A hot-melt adhesive composition having a melt viscosity ofabout 3,000 to about 25,000 centipoise at 135° C., a cone penetrationvalue as measured by ASTM Procedure D-1403 of at least 10 dmm, and aRing and Ball softening point of about 90° C. to about 125° C., saidcomposition comprising a blend of:(a) at least one substantiallyamorphous propylene/hexene copolymer having an acid number of less thanabout 0.5, (b) at least one tackifier, and (c) at least onesubstantially crystalline, low viscosity hydrocarbon wax containingsubstantially no propylene and having a melt viscosity of from about 3to about 4,000 centipoise at 150° C. and a melting point of from about90° C. to about 125° C., the concentrations of components (a), (b), and(c) being such that said adhesive composition has elastic delaminationresistance of at least about 4 hours wherein elastic delaminationresistance is the length of time a polyethylene to elastic bond canwithstand the stress of elastic relaxation at body temperature.
 2. Theadhesive composition of claim 1 wherein said adhesive composition has aviscosity of about 4,000 to about 10,000 centipoise at 135° C. and aRing and Ball softening point of about 100° C. to about 120° C.
 3. Thecomposition of claim 1 wherein said hydrocarbon wax is a polyethylenewax having a melt viscosity of from about 3 to about 1,000 centipoise at150° C., a melting point of from about 105° C. to about 125° C., and apenetration hardness of about 0.1 to about
 10. 4. The adhesivecomposition of claim 1 wherein component (a) is present in an amount ofabout 30 to about 70 weight percent, component (b) is present in anamount of about 20 to about 60 weight percent, and component (c) ispresent in an amount of from about 1 to about 10 weight percent.
 5. Theadhesive compositions of claim 1 wherein said elastic delaminationresistance is at least about eight hours.
 6. The adhesive compositionsof claim 1 which has a molten Gardner color as measured by ASTMProcedure D-1544 of less than about 7, a tensile strength as measured byASTM Procedure D-638-72 of at least about 10 psi, a bond strength of atleast about 200 grams per 2.1 mg per inch coating weight, and whereinsaid elastic delamination resistance is at least about 24 hours.
 7. Theadhesive composition of claim 6 wherein said cone penetration value isat least about 20 dmm, said molten Gardner color is less than about 4,said tensile strength is about 20 to about 50 psi, said bond strength isat least 300 grams per 2.1 mg per inch coating weight, and said elasticdelamination resistance is at least about 100 hours.
 8. The compositionof claim 1 additionally containing at least one antioxidant, at leastone additional additive or a mixture thereof.
 9. A hot-melt adhesivecomposition having a melt viscosity of about 3,000 to about 25,000centipoise at 135° C., a cone penetration value as measured by ASTMProcedure D-1403 of at least 10 dmm, and a Ring and Ball softening pointof about 90° C. to about 125° C., said composition comprising a blendof:(i) about 30 to about 70 weight percent of at least one substantiallyamorphous propylene/hexene random copolymer containing from about 20 toabout 50 weight percent of 1-hexene said copolymer having a meltviscosity of from about 2,000 to about 20,000 centipoise at 190° C. (ii)about 20 to about 50 weight percent of at least one solid tackifiercomprising hydrocarbon resins or polyterpene resins said tackifierhaving a softening point of from about 70° C. to about 145° C. (iii) 0to about 30 weight percent of at least one liquid tackifier having aviscosity of from about 10,000 to about 50,000 centipoise at 23° C. anda Ring and Ball softening point of from about 5° C. to about 30° C.,(iv) from about 1 to about 10 weight percent of at least one highdensity, substantially crystalline, low viscosity hydrocarbon waxcontaining substantially no propylene and having a melt viscosity offrom about 3 to about 4,000 centipoise at 150° C. and a melting point offrom about 90° C. to about 125° C., and (v) 0 to about 30 weight percentof at least one plasticizing oil.
 10. The adhesive composition of claim9 which has a molten Gardner color as measured by ASTM Procedure D-1544of less than about 7, a tensile strength as measured by ASTM ProcedureD-638-72 of at least about 10 psi, a bond strength of at least about 200grams per 2.1 mg per inch coating weight, and wherein the elasticdelamination resistance is at least about 4 hours.
 11. The adhesivecomposition of claim 10 wherein said cone penetration value is at leastabout 20 dmm, said molten Gardner color is less than about four, saidtensile strength is about 20 to about 50 psi, said bond strength is atleast about 300 grams per 2.1/mg per inch coating weight, and saidelastic delamination resistance is at least about 8 hours.
 12. Thecomposition of claim 11 wherein said delamination resistance is at leastabout 24 hours.
 13. The composition of claim 9 wherein component (i)comprises: about 40 to about 65 weight percent of at least onesubstantially amorphous propylene/hexene random copolymer containingfrom about 30 to about 40 weight percent of 1-hexene, said copolymerhaving a melt viscosity of from about 4,000 to about 20,000 centipoiseat 190° C. and having a Ring and Ball softening point of about 100° C.to about 134° C.,Component (ii) comprises: about 25 to about 40 weightpercent of at least one solid tackifier, comprising hydrocarbon resinsor polyterpene resins said solid tackifier having a softening point offrom about 120° C. to about 145° C., Component (iii) comprises: fromabout 15 to about 25 weight percent of at least one liquid tackifierhaving a viscosity of from about 20,000 to about 40,000 centipoise at23° C., a Ring and Ball softening point of from about 10° C. to about20° C., and a Tg of about -10° C. to about -30° C., Component (iv)comprises: from about 3 to about 7 weight percent of at least onesubstantially crystalline, low viscosity polyethylene wax having a meltviscosity of from about 3 to about 1,000 centipoise at 150° C. and amelting point of from about 105° C. to about 125° C. and Component (v)comprises about 0 percent of a plasticizing oil.
 14. The composition ofclaim 9 wherein component (i) comprises: about 40 to about 65 weightpercent of at least one substantially amorphous propylene/hexene randomcopolymer containing from about 30 to about 40 weight percent of1-hexene, said copolymer having a melt viscosity of from about 4,000 toabout 20,000 centipoise at 190° C. and having a Ring and Ball softeningpoint of about 100° C. to about 134° C.,Component (ii) comprises: about25 to about 40 weight percent of at least one solid tackifier,comprising hydrocarbon resins or polyterpene resins said solid tackifierhaving a softening point of from about 120° C. to about 145° C.,Component (iii) comprises: about 0 percent of a liquid tackifier.Component (iv) comprises: from about 3 to about 7 weight percent of atleast one substantially crystalline, low viscosity polyethylene waxhaving a melt viscosity of from about 3 to about 1,000 centipoise at150° C. and a melting point of from about 105° C. to about 125° C., andComponent (v) comprises: about 5 to about 20 weight percent of at leastone plasticizing oil.
 15. The adhesive composition of claim 9 whereinsaid solid tackifier is a C₅ hydrocarbon resin or polyterpene resin. 16.The adhesive composition of claim 9 wherein said liquid tackifier is asynthetic polyterpene.
 17. The adhesive composition of claim 9additionally comprising an antioxidant, an additional additive or amixture thereof.
 18. The adhesive composition of claim 9 having aGardner color of less than about
 3. 19. A hot-melt adhesive compositionhaving a melt viscosity of about 5,000 to about 9,000 at 135° C., a conepenetration value as measured by ASTM Procedure D-1403 of at least 10dmm, a Ring and Ball softening point of about 112° C. to about 125° C.,and a Gardner color of less than about 7, said composition comprising ablend of:(a) about 43 to about 53 weight percent of at least onesubstantially amorphous propylene/hexene random copolymer containingfrom about 32 to about 36 weight percent of 1-hexene, said copolymerhaving a melt viscosity of from about 5,300 to about 6,100 centipoise at190° C. and a Ring and Ball softening point of about 129° C. to about134° C., (b) about 24 to about 29 weight percent of at least one solidtackifier comprising a hydrocarbon resin, said solid tackifier having aRing and Ball softening point of about 125° C. to about 135° C. and amelt viscosity at 190° C. of about 600 to about 1,600 centipoise, (c)about 18 to about 22 weight percent of at least one liquid tackifiercomprising a hydrocarbon resin, said liquid tackifier having a Ring andBall softening point of about 10° C. to about 20° C., a melt viscosityof about 20,000 to about 40,000 centipoise at 23° C. and a Tg asmeasured by DSC of about -10° C. to about -30° C., (d) about 3 to about7 weight percent of at least one high density, substantiallycrystalline, low viscosity polyethylene wax containing substantially nopropylene and having a melt viscosity of from about 300 to about 700centipoise at 150° C. and a melting point of about 120° to about 125°C., and (e) about 0.3 to about 0.6 weight percent of at least oneantioxidant.
 20. The adhesive composition of claim 19 having a meltviscosity of about 7,400 at 135° C., a Ring and Ball softening point ofabout 117° C., and a Gardner color of less than about 3, andwherein:component (a) comprises: about 48 weight percent of saidamorphous propylene/hexene copolymer containing about 34 weight percent1-hexene, said copolymer having a Ring and Ball softening point of about132° C. and a melt viscosity of about 5,700 centipoise at 190° C.,component (b) comprises: about 27 weight present of said liquidtackifier having a Ring and Ball softening point of about 130° C. and amelt viscosity at 190° C. of about 1,000 centipoise. component (c)comprises: about 20 weight percent of said liquid tackifier having aRing and Ball softening point of about 20° C., a Tg of about -20° C.,and a melt viscosity of about 40,000 centipoise at 23° C., component (d)comprises: about 5 weight percent of said polyethylene wax having amelting point of about 123° C., a density of about 0.95 g/cc, and a meltviscosity at 150° C. of about 500 centipoise, and component (e)comprises: about 0.5 weight percent of said antioxidant.